Recent active introduction of renewable energy, such as photovoltaics (PV: solar power generation) and wind power generation, has resulted in sharp increase in a reverse current causing problems in a system such as frequency fluctuation (lack of back up capacity in the system) and voltage rise, especially in islands where a grid is small. Due to such problems, an application for the PV connection might take time or installation of the PV might not even be permitted.
Countermeasures to address such problems include reducing an output from the PV or even stopping the output from the PV for a predetermined period of time when a frequency or voltage of a power distribution system increases. In recent years, a system that cooperates with higher level systems to address the problems has been proposed.
In an automatic power distribution system in disclosed in PTL 1, a dispersed power source (PV) is connected with a power distribution line through a smart meter, and a voltage value at a node at which the dispersed power source is connected with the power distribution line and a voltage value of a power distribution substation are collected, and an amount of power that is transmitted to the power distribution line and measured by the smart meter is collected through a meter data management system. When the voltage value at the node exceeds a voltage target value, the automatic power distribution system calculates a reactive power control amount by using the voltage value at the node, a voltage value of a power distribution substation, the voltage target value, a power amount acquired by the smart meter, and a power distribution line impedance of the node. Then the automatic power distribution system transmits a command value indicating the reactive power control amount distributed to the dispersed power sources to the smart meter through a meter data management system, and thus controls the reactive power of a solar light inverter.